Optimal strategies for sending information through a quantum channel

E. Bagan, M. Baig, A. Brey, R. Muñoz-Tapia, R. Tarrach

Research output: Contribution to journalArticleResearchpeer-review

57 Citations (Scopus)


Quantum states can be used to encode the information contained in a direction, i.e., in a unit vector. We present the best encoding procedure when the quantum state is made up of N spins (qubits). We find that the quality of this optimal procedure, which we quantify in terms of the fidelity, depends solely on the dimension of the encoding space. We also investigate the use of spatial rotations on a quantum state, which provide a natural and less demanding encoding. In this case we prove that the fidelity is directly related to the largest zeros of the Legendre and Jacobi polynomials. We also discuss our results in terms of the information gain. © 2000 The American Physical Society.
Original languageEnglish
Pages (from-to)5230-5233
JournalPhysical Review Letters
Publication statusPublished - 1 Jan 2000


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